Vermox is a trade name for mebendazole. There are all sorts of posibilities of how/why a treatment for one condition may impact on a wholly unrelated condition. There are some suggestions that mebendazole may have an anti fungal action (can't locate ref) and also impacts on insulin production http://www.ncbi.nlm.nih.gov/pubmed/6381196
IVI
Good point, although can be hard to form a conclusion. Perhaps diabetes is often mediated by parasitic or fungal infection, for example, and the mebendazole helped manage that.
Anyway, the effect of Vermox/mebendazole on my CFS symptoms was dramatic and started about 4 hours after the first dose. So whatever it does, it works quickly.
When this happened to me, I believe about 1998, there was little info about parasites in CFS. Then in 2000 Dr.Larry Klapow discovered a novel roundworm in the lungs of CFS patients that he named Cryptostrongylus pulmoni (C.pulmoni). He actually patented a treatment, cured a few CFS patients, got little support and I believe eventually gave up on CFS research... So I have wondered whether the Vermox somehow stopped C.pulmoni activity, or something like that. Who knows...we get so little help and there are many good leads like this that are forgotten.